DTC P0171: Fuel Trim Malfunction (Too Lean) - IMPREZA 2.2L, Legacy & Outback 2.5L M/T & Outback Sport

Perform basic diagnostic procedure. See BASIC DIAGNOSTIC PROCEDURE . If only DTC P0171 exists, perform DTC P0172. See DTC P0172: FUEL TRIM MALFUNCTION (TOO RICH) - IMPREZA 2.2L, LEGACY & OUTBACK 2.5L M/T & OUTBACK SPORT . Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .